1. Field of the Invention
This invention relates to a fatigue-resistant bracket structure, and more particularly to such structure braced with a friction-dampened gusset.
The instant invention is related to my copending U.S. patent application entitled Plug-Welded Gusset, Ser. No. 07/739,891, filed on Aug. 2, 1991. There, a footed gusset, preferably a strap that spans the joint and has feet bent from its ends for contacting the surfaces to be braced, is plug-welded to attach the gusset.
2. Description of the Prior Art
The conventional gusset for imparting fatigue resistance to an angular rigid joining of convergent surfaces is an "erect" or "plate-type" rigid gusset. For the usual right-angle, weldable, metal joint, such gusset typically is weldable metal triangle or a trapezoid that fills in all or almost all of a right angle at the joint; the legs of such triangle, or the slanting sides of such trapezoid, generally will be welded with fillet welds that box the outer ends and the long edges of the gusset which contact the metal surfaces being so braced.
The prior art appears to be devoid of suggesting the use of a friction-dampened gusset for rendering a bracket structure of a conveyance resistant to failure from fatigue. Such a bracket may be, for example, a hanger bracket for an air chamber of an automotive truck. In conveyances a bracket structure is likely to be subject to extended periods of vibration. Conveyances here include vehicles generally such as autos, trains, wagons and cycles, and they also include ships, aircraft and spacecraft.
Heretofore, shock-arresting frictional snubbers in the form of plates sliding in slots have been proposed for an automobile chassis (U.S. Pat. No. 1,508,346) and for engine mountings (U.S. Pat. No. 1,751,743), both to obtain a smoother ride.
Also, for arresting occasional explosive or seismic shocks in ships and in buildings, there have been proposed various other friction-dampened connections. These are shown in U.S. Pat. Nos. 2,968,458, 4,409,765 and 4,615,157.
A rigid bracket structure, apart from any gusset, may be basically a bent piece of stiff material such as a piece of flat, weldable metal. More frequently, however, the structural portions being braced are two intersecting members joined by welding such as fillet welding. Frequently, the elements of a bracket will comprise a ferrous metal such as steel, and most of the intersections or bends so braced will project from each other at substantially a right angle. The ordinary fillet weld is a weld of approximately triangular cross section joining two surfaces at right angles to each other in a lap joint, T-joint, or corner joint. However, in this application, the intersection of the two surfaces also may form an acute or obtuse angle instead, and the intersection may define a straight or curved line that may be in a single plane or in more than one plane.
The instant invention has been found to be surprisingly effective for prolonging the fatigue life of a bracket. The fatigue life of welded brackets for automotive use, when made in accordance with the principles of this invention, may be easily 25-300 times longer than the fatigue life of conventional brackets now made for the same purposes.
Additionally, the installation of the instant friction-dampened gusset can be simple and quick, and the resulting inventive bracket can provide consistently high fatigue-resisting performance that is particularly advantageous for mass production of the item.